Trical manufacturing co



Nov. 1, 1927. 1,647,329

' C.F.ADOLPH MAGNETO MI CROPHONI C RELAY Filed Dec. 21, 1925 wwWW.

Patented Nov. 1, 1927.

. 1,647,329 UNITED STATES PATENT orrics.

' CARI. FREDERICK ADOLPH, or LONDON, Enemies, nssrenoa 'ro ivnw WILSON ELEC- TRICAL MANUFACTURING co. D. 01? onnon, ENGLAND.

MAGNETO-MICROPHQNIC RELAY.

Application filed December 21, 1925, Serial No. 76,746, and'in'Great Britain March 31, 1925.

I This invention relates to a magneto-microphonic relay of-the kind in which a microphone unit whose movable carbon electrode is combined with an armatureelement, is placed against the magnet poles of a watch receiver so as to be aifected bythe currents passing through the magnet coils.

The object of theinvention is to produce a microphone unit which is of simple construction and which allows of being readily detached for keeping the armature plate and the pole pieces of the magnetfree from dust; and particles liable to interfere with the free,

functioning of the diaphragm. With this object in view the invention consists in the provision of a microphone unit in the form of a bar adapted to bridge the watch receiver and to be retained in position thereon merely by the magnetic attraction. Preferably the microphone electrodesare. accommodated in a casing of U-shaped crosssection whereby they are supported on the Watch receiver,and. they are controlled by armature plate 6 and the pole pieces. The

a spring and a screw whereby they can be adjusted within the casing for regulating their position relative to the magnet poles.

A very sensitive microphone is obtained by the employment of a substantially lozengeshaped armature-plate which is fastened by means of its tapering ends to, its support,

Fig. 1 of the accompanying drawings represents a sectional view of one form of micro phone construction, and

Fig.2, an inverted plan of the same. Fig. 3 is a sectional view of a modified form, and I Fig. 4, an end View of the latter. Fig. 5 is a side view of a further modification, and

Fig. 6 is a perspective View showing the microphone bar and the watch receiver mounted on a stand for use as a sound ampli fier in connection with radio receivers.

J The :microphone is provided, .in known;

manner, witha carbon block a. between which and a carbon diaphragm b a plurality of carbon granules are supported so as to vary the electric resistance between two terminals c and d under the vibratory movements of the diaphragm b. Secured to the v outside of the latter, is an armature plate a which causes the diaphragm plate to vibrate under the influence of the ma etic impulses impressed on; a watch receiver f against Q N Y which the microphoneissupported with the Fig. 5 where the carbon electrodesam 1 aphragm b and the armature plate 6 are connected by screws 71. direct to the carbonblock a which is correspondingly elongated. The block is accommodated in a metal casing z of U-shaped cross section and is controlled in the latter by a screw-spindle is, an ebo'nite 1 nut in the form of a hand-Wheel Z and a blade spring m which abuts againstthe block and againstthe casing. The screw-spindle 7c is connected to the. carbonblock and in sulated from the casing z and from the spring by means ofthe nut Z. i The spring m'urges: the carbon block towards the pole pieces g, and the nut l which holds it back, is adjusted by regulating the distance between the terminal screw '0 is insulated from the carbon ,blockand from the casing and connected electrically with the armature plate 6 whence the carbon passes through the carbon elements and through the screw spindle to the terminal d.

In the modified construction shown in Figs. 3 and 4, the carbon block is connected by means-of the spindle k to a metal yoke 11?. which is insulated, for instance by mica washers, from the blocktas well as from the spindle. The diaphragm b and thearmature plate 6 are secured to the down-turned ends of the yoke a which is held in a casing 71 as previously described. The terminal screw c'is connected to the casing i and the current passes through the latter,- through the spring m and through the yoke a to the armature plate and thence through the car-. bon elements to the terminal d.

In both constructions the armature plat-e e is substantially lozenge-shaped, as shown in Fig. 2, i. e'., it tapers at both ends towards the connecting screw it where, owing to the reduced width of the plate, very little resistance will be offered to "its vibratory movements. Thus a very sensitive microphone will be obtained.

microphone bar may be simplified as shown In the case of smaller'instruments, the

enclosed in a casing 0 which differs from the casing 27 in that it is provided with end members which are bent twice to form supports for the diaphragm i) and the plate 6, these elements being secured direct to the casing. In this construction the supporting edges of the casing 0 are placed initially so that the armature plate 0 will be correctly positioned by the casing without readjustment.

Fig. 6 illustrates the employment of the microphone bar in a sound amplifier for use in connection with-radio receivers.

The watch receiver f is hinged by means of a radial arm 3) which may be adapted to house a transformer. The cover f of the receiver is slotted diametrically to admit the microphone bar to the receiver magnet relative to udiichthe armature plate is adjusted by means of the hand Wheel Z. The microphone bar can be pulled away from the receiver in opposition to the magneticattraction whenever inspection of the interior isrequired. The amplifier is connected to the radio set my means o'fzwires 1" which lead a the received impulses through the watch receiver f. A local battery is connected to terminal studs 8 which lead the current through the microphone bar and through the primary coil of the transformer. Wires 1- connect the bar with the battery and with the transformer. The secondary coil of the transformer is connected to terminal studs u to which the phones or a loud-speaker are also connected. The hinged arm p 'allows the watch receiver and the microphone bar to be tilted backwards and forwards for regulating the gravital distribution of the carbon granules in a manner known per se in connection with amplifiers of this type.

I claim:

1. In a magneto-microphonic relay of the character described, the combination with a watch-shaped receiver casing and its electromagnet, of a bar-shaped microphone unit adapted to bridge the receiver casing, and a combined vibratory armature plate and carbon electrode held in said microphone unit and adapted to retain the latter in position on the receiver casing merely by the magnetic attraction between the armature plate and the receiver magnet.

2. The structure claimed in claim 1 including a casing vof U-shaped cross-section enclosing the microphone unit and supporting it on the edge of the receiver casing against the magnetic attraction, and means for adjusting the microphone unit within said casing to regulate the distance of the armature plate from the magnet poles.

3. In a magneto-microphonic relay of the character described, the combination with a watch-shaped receiver casing and its electro-magnet, of a microphone casing of U- shaped cross-section bridging said receiver casing, a bar-shaped microphone unit having a vibratory carbon electrode and being housed in said casing, a screw-spindle secured to the microphone unit and projecting through the back of the microphone casing, a blade spring arranged between the microphone unit and its casing, a nut in the form of hand wheel arranged on said. spindle outside the casing so as to co-operate with the spring for supporting the microphone unit in the casing, and a substantially lozenge-shaped armature plate connected to the vibratory carbon electrode of the micro: prone unit and fastened to the latter by means of its tapering ends so that it faces the magnet poles and holds the microphone tion thereon merely by the magnetic attrac-- tion between the armature plate and the receiver magnets, and means for regulating the position of the armature pl'ate relative to the magnet poles.

CARL FREDERICK ADOLPH. 

